RFR: 8319048: Monitor deflation unlink phase prolongs time to safepoint [v8]

[Aleksey Shipilev]

On Mon, 20 Nov 2023 21:21:50 GMT, Daniel D. Daugherty <dcubed at openjdk.org> wrote:

>> Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains 15 additional commits since the last revision:
>> 
>>  - No need for vm.flagless
>>  - Use precise deflated_count
>>  - Rework option handling
>>  - Merge branch 'master' into JDK-8319048-monitor-deflation-unlink
>>  - Merge branch 'master' into JDK-8319048-monitor-deflation-unlink
>>  - Merge branch 'master' into JDK-8319048-monitor-deflation-unlink
>>  - Move unlink_batch init to proper place
>>  - Add invariant checking
>>  - Merge branch 'master' into JDK-8319048-monitor-deflation-unlink
>>  - Fix test after recent test infra renames
>>  - ... and 5 more: https://git.openjdk.org/jdk/compare/55b9955d...5c41e46e
>
> I'm reading thru this PR yet again...
> 
> @fisk - In a comment above you have:
> 
>> 4. Walk said deflated monitors again through said external data structure, and unlink them from the in-use list
> 
> which is exactly the same as:
> 
>> 3. Walk said deflated monitors again through said external data structure, and unlink them from the in-use list
> 
> so I think that's an error. I think you mean that step 4 should be where we delete the ObjectMonitors
> and not unlink them again which we can't do...

I assume @dcubed-ojdk is back from holidays, let's see if we can get his blessing today :)

-------------

PR Comment: https://git.openjdk.org/jdk/pull/16412#issuecomment-1828176315